Freestanding Catalyst Layers: A Novel Electrode Fabrication Technique for PEM Fuel Cells via Electrospinning

Abstract

To propel the commercial success of fuel cells, increased Pt catalyst utilization is preeminent. To achieve this, advanced 3D scaffold electrode architecture with controllable porosity, thickness, etc. should be developed. Here, we present a novel technique for the fabrication of electrode structures through electrospinning, which is not only tailorable, but inexpensive and scalable. The structure is freestanding and contains carbon nanotube‐enforced carbon nanofibers, which give the electrode its structure. Pt is decorated on the surface of the fiber structures through impregnation of a Pt precursor and successive reduction. The electrode structure is hot‐pressed by inserting it between a gas diffusion layer (GDL) and a membrane to form the cathode. The novel fabrication technique is versatile and can be used to prepare electrodes of different morphologies. In this work, we demonstrate the technique by preparing a highly porous network, which shows a very high Pt utilization of approximately 90% for a loading of 0.3 mgPt cm−2. In comparison, a standard electrode prepared via a hot‐spray technique has a catalyst utilization of 60% for the same loading.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

“…The high porosity of a nonwoven mat of nanofibers and the interconnection among the pores can facilitate the mass transport of reactants, provide extensive contact between reactants and active sites on electrocatalysts, and promote electron and proton conduction. For the mats consisting of Pt-covered nanofibers, they can directly serve as electrodes. , Additionally, a uniform distribution can be readily achieved for the Pt/C powder in a fibrous cathode by directly electrospinning the catalyst ink, enabling efficient proton transport and oxygen diffusion to the catalytic sites during the operation of a fuel cell. , Over the past 2 decades, nanofibers made of polymers, metals, ceramics, and carbon have all been extensively explored for the fabrication of fuel cells in an effort to improve their efficiency and durability while reducing the cost. ,, …”

Comparison of Electrospun Carbon−Carbon Composite and Commercial Felt for Their Activity and Electrolyte Utilization in Vanadium Redox Flow Batteries

“…In the last couple of years, researchers showed an increasing interest in electrospinning, a versatile technique which facilitates tailoring a broad range of organic polymers to fabricate thin fibers and fiber mats, amongst others for electrochemical energy applications . This efficient approach can be used to prepare high surface area electrodes of carbon nanofibers (CNFs) on a large scale, which then may be used in fuel cells, lithium ion or redox flow batteries . In our previous work, we demonstrated the use of electrospinning to prepare polyacrylonitrile (PAN)‐based CNFs and their successful application as free‐standing electrode for VRFBs.…”

Strategies to Hierarchical Porosity in Carbon Nanofiber Webs for Electrochemical Applications

“…A very efficient and upscalable approach to prepare a CNF network is via the electrospinning and carbonization of a polymer solution [3,4]. Furthermore, CNF webs obtained via electrospinning can often be designed to possess sufficient mechanical stability and through-plane electric conductivity to be used as free-standing electrodes, as shown in recent studies on batteries [5,6], supercapacitors [7][8][9], fuel cells [10][11][12], vanadium redox-flow [13] and Li-O 2 batteries [14]. This technique may not only simplify the electrode fabrication process, but also maximizes the macropore volume in the electrode and avoids binders, otherwise necessary with dispersed CNFs or other carbon powder materials to form the electrode.…”